This project is designed to experimentally define the pathophysiology and formulate a management approach to the complication of infection associated with prosthetic vascular grafting. We have demonstrated in our laboratory that transient bacteremia is a mechanism for prosthetic vascular graft infection when the bacteremic exposure occurs in the early post-operative period. This protocol will determine the duration, following implantation, that a prosthetic vascular graft remains susceptible to infection of bacteremic origin. Abdominal aortas will be replaced with prosthetic vascular grafts and exposed to bacteremic challenge at progressive time intervals following graft implantation. Subsequent graft harvesting and culture will define the period of vulnerability to infection. This project will also evaluate a series of vascular graft alternates that may be used as arterial replacements in an infected or contaminated field following removal of an infected prosthetic graft. The alternate vascular conduits to be evaluated will include autograft and homograft arteries and veins, as well as a compound vascular prosthesis consisting of a monofilament, Dacron mesh- supported autogenous fibrous tissue tube. If autograft or allograft fresh tissue vessels prove to be satisfactory replacements in infected fields, then this project will evaluate the duration that homograft arteries and veins can be stored, using freezing, prior to use in an infected field and still function as a live tissue graft following implantation.